The present invention relates to a stapler apparatus for stacking and stapling sheets with images formed by an image forming apparatus such as a copier, printer or printing machine to form a bundle, a sheet finishing apparatus used as an end unit apparatus of an image forming apparatus, and an image forming apparatus equipped with the sheet finishing apparatus.
In general, a stapler apparatus for binding sheets includes a head unit with staple drive means called a driver for driving a staple and an anvil unit with bending means such as a clincher for bending leading ends of the staple. The head unit and the anvil are arranged at opposing positions with a sheet bundle therebetween. One of the head unit and the anvil unit is moved downward rapidly to penetrate a U-shaped staple into a sheet bundle, and the anvil unit bends the leading ends of the staple. Such an apparatus has been well known in the art.
A variety of sheet finishing apparatuses have been known as an end unit apparatus of an image forming apparatus, in which sheets with images are stacked and aligned on a processing tray. Then, a stapler apparatus disposed in the processing tray binds the sheet bundle, and the sheet bundle is stored on a stacking tray.
The stapler apparatus disposed in such a sheet finishing apparatus is provided with a staple cartridge in the head unit thereof. A roll or a sheet of straight staples joined together into a band or belt shape is stored in the cartridge. A former member disposed in the head unit bends the straight staple into a U-shape, and the driver member drives the U-shaped staple into the sheet bundle. A clincher disposed in the anvil bend bends the leading ends of the staple to bind the sheet bundle.
An operation of stapling is completed in a series of movements of the head unit from a position away from the anvil unit to a position contacting the anvil unit. A rotating cam connected to a drive motor directly moves the anvil unit, or a servo mechanism such as a lever moves the anvil unit.
Accordingly, the head unit and anvil unit are arranged apart for a distance with the sheet bundle therebetween, and move (normally, one of the head unit and anvil unit) rapidly to a contact position, so that the staple penetrates into the sheet bundle. It is possible that a loud noise is generated during the stapling operation. If a finger of an operator or other foreign object is inserted into the apparatus during the operation, it is possible to cause an accident or malfunction.
Recently, the size of the sheet finishing apparatus has been reduced, and the stapler apparatus tends to be disposed near a paper removal outlet of a stacker for storing the sheet bundle. In such a structure, it is possible that an operator touches the mechanism of the stapler apparatus when removing a sheet. It is also possible that the operator touches the apparatus when a problem such as staple jam occurs. If the stapler apparatus is operated when the operator touches the apparatus, the operator may get injured. Further, the stapler apparatus causes the problem of generating noise during the operation or jamming a foreign object.
In order to prevent the problems of noise or intrusion of a foreign object, an apparatus has been known in which rollers are provided for discharging the sheet bundle after stapling. The rollers are arranged to move vertically between an open position and a closed position, and the rollers are closed during the operation of stapling.
Japanese Patent Publication (Kokai) No. 2001-058756 has disclosed such an apparatus in which rollers are disposed at a side of a trailing edge of the sheet bundle relative to a stapler disposed at a leading edge of the sheet bundle. The rollers move to contact the sheet bundle during the stapling operation. However, such a structure is limited to an apparatus with a specific configuration. In particular, in an apparatus in which a stapler apparatus is arranged at the leading edge of the sheet bundle and the sheet bundle is removed from a backside of the stapler apparatus, it is difficult to prevent a finger from inserting or a foreign object from jamming. In the apparatus disclosed in Japanese Patent Publication (Kokai) No. 2001-058756, it is possible that the stapling operation could accidentally occur when the rollers are retracted from the sheet bundle and a finger of an operator is inserted.
When the stapler apparatus runs out the staples after the binding operation, it is necessary to replace the staple cartridge to replenish the staples. In addition, when a staple is jammed because of a wrong operation of stapling, it is necessary to remove the stapler apparatus from the finishing apparatus. In a conventional apparatus, a part of an external cover of the finishing apparatus is arranged to open, and faces a frame of the finishing apparatus mounted with the stapler apparatus. For example, in the stapler apparatus disclosed in Japanese Patent Publication (Kokai) No. 2001-058765, a cover is opened so that a staple cartridge is removed from the stapler apparatus. When a staple is jammed, the jam is handled while the stapler apparatus is still mounted to the finishing apparatus. In a stapler apparatus disclosed in Japanese Patent Publication (Kokai) No. 09-267967, it is necessary to remove the stapler apparatus from a finishing apparatus to replace a staple cartridge.
In the stapler disclosed in Japanese Patent Publication (Kokai) No. 2001-058765, it is necessary to remove the jam while the stapler apparatus is still mounted to the finishing apparatus, thereby complicating the work and deteriorating operability. In the stapler apparatus disclosed in Japanese Patent Publication (Kokai) No. 09-267967, the stapler apparatus is detachably mounted to the finishing apparatus. It is necessary to frequently remove the unit each time when the staples are replenished and return the unit at a right position, thereby making the work tedious. In particular, when the stapler apparatus is arranged at a backside of the sheet finishing apparatus, it is difficult to handle a staple jam.
In view of the problems describe above, an object of the present invention is to provide a stapler apparatus applicable to a variety of sheet finishing apparatuses and a sheet finishing apparatus provided with the stapler apparatus, wherein it is possible to prevent a finger of an operator or a foreign object from inserting into a staple mechanism. Even if a finger of an operator or a foreign object is inserted into the staple mechanism, it is still possible to prevent an injury or an accident.
Another object of the present invention is to provide a stapler apparatus mounted to a sheet finishing apparatus, wherein it is easy to replenish staples or remove a jammed staple, and it is possible for an operator to safely mount or remove a stapler apparatus relative to a sheet finishing apparatus.
Further objects and advantages of the invention will be apparent from the following description of the invention.